The eye is a complex anatomical component of the visual system that collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. The eye provides the ability to recognize differences in two aspects of light: brightness (based on the luminance of light) and color (based on the wavelength of light). Cones are a class of photoreceptors in the back of the eye (i.e., the retina) that provide well-defined visual acuity and color vision when in bright light. Rods are highly sensitive photoreceptors in the outer regions of the retina to provide optical information in reduced lighting for night vision as well as assist in peripheral vision in brighter lighting conditions.
The eye has a complex structure with various parts or components that cause optical reflections. The main locations of eye reflection include, for example, corneal reflections of light reflected off the cornea, iris reflections of light reflected off the iris, and retroreflections of light reflected off the retina. Such reflections can cause adverse effects in some applications such as the red-eye effects in photographing and may also be used in various optical systems, e.g., eye tracking devices.